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Parkinson's disease (PD) is a progressive disorder characterized by the apoptosis of dopaminergic neurons in the basal ganglia. This study explored the potential effects of aminophylline, a non-selective adenosine A1 and A2A receptor antagonist, on catalepsy and gait in a haloperidol-induced PD model. Sixty adult male Swiss mice were surgically implanted with guide cannulas that targeted the basal ganglia. After seven days, the mice received intraperitoneal injections of either haloperidol (experimental group, PD-induced model) or saline solution (control group, non-PD-induced model), followed by intracerebral infusions of aminophylline. The assessments included catalepsy testing on the bar and gait analysis using the Open Field Maze. A two-way repeated-measures analysis of variance (ANOVA), followed by Tukey's post hoc tests, was employed to evaluate the impact of groups (experimental × control), aminophylline (60 nM × 120 nM × saline/placebo), and interactions. Significance was set at 5%. The results revealed that the systemic administration of haloperidol in the experimental group increased catalepsy and dysfunction of gait that paralleled the observations in PD. Co-treatment with aminophylline at 60 nM and 120 nM reversed catalepsy in the experimental group but did not restore the normal gait pattern of the animals. In the non-PD induced group, which did not present any signs of catalepsy or motor dysfunctions, the intracerebral dose of aminophylline did not exert any interference on reaction time for catalepsy but increased walking distance in the Open Field Maze. Considering the results, this study highlights important adenosine interactions in the basal ganglia of animals with and without signs comparable to those of PD. These findings offer valuable insights into the neurobiology of PD and emphasize the importance of exploring novel therapeutic strategies to improve patient's catalepsy and gait.

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In this study, a pharmacological approach, together with the paw pressure test, was used to investigate the role of dopamine and its receptors in the peripheral processing of the nociceptive response in mice. Initially, the administration of dopamine (5, 20, and 80 ng/paw) in the hind paw of male Swiss mice (30-40 g) promoted antinociceptive effects in a dose-dependent manner. This was considered a peripheral effect, as it did not produce changes in the nociceptive threshold of the contralateral paw. The D2, D3, and D4 dopamine receptor antagonists remoxipride (4 µg/paw), U99194 (16 µg/paw), and L-745,870 (16 µg/paw), respectively, reversed the dopamine-mediated antinociception in mice with PGE2-induced hyperalgesia. The D1 and D5 dopamine receptor antagonists SKF 83566 (2 µg/paw) and SCH 23390 (1.6 µg/paw), respectively, did not alter dopamine antinociception. In contrast, dopamine at higher doses (0.1, 1, and 10 µg/paw) caused hyperalgesia in the animals, and the D1 and D5 receptor antagonists reversed this pronociceptive effect (10 µg/paw), whereas the D2 receptor antagonist remoxipride did not. Our data suggest that dopamine has a dual effect that depends on the dose, as it causes peripheral antinociceptive effects at small doses via the activation of D2-like receptors and nociceptive effects at higher doses via the activation of D1-like receptors.

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Dentre os sistemas neurais responsáveis pela ingestão dos alimentos, destaca-se a via dopaminérgica mesolímbica que, através da liberação de dopamina nos núcleos de accumbens, desperta prazer e motivação para recompensas químicas e naturais. Esta via de recompensa age através dos receptores dopaminérgicos transmembranares, que variam de DRD1 a DRD5. Desta forma, considerando os efeitos prazerosos despertados pela ingestão alimentar, é plausível que variações genéticas em genes do sistema dopaminérgico possam ter um papel na arquitetura genética da obesidade. Este estudo tem como objetivo realizar uma revisão narrativa da literatura sobre a influência de variantes genéticas nos receptores dopaminérgicos em fenótipos relacionados com a obesidade. Em conjunto, os principais achados desta revisão indicaram que os genes codificadores dos receptores DRD2 e DRD4 possam ser os mais relevantes no contexto da obesidade e fenótipos relacionados. No entanto, a obesidade é uma doença complexa e multifatorial e novos estudos são ainda necessários para uma melhor compreensão do impacto da dopamina nos desfechos relacionado à obesidade. É importante também destacar que esses efeitos podem ser específicos para subgrupos de pacientes e que outros fatores, além das variantes genéticas, devem ser considerados. (AU)

Among the neural systems responsible for food ingestion, the mesolimbic dopaminergic pathway stands out by eliciting pleasure and motivation for chemical and natural rewards through the release of dopamine in the nucleus accumbens. This reward pathway is regulated by transmembrane dopaminergic receptors, which range from DRD1 to DRD5. Thus, considering the pleasurable effects aroused by food intake, it is plausible that genetic variations in genes of the dopaminergic system may have a role in the genetic architecture of obesity. This study aims to conduct a narrative review of the literature on the influence of genetic variants of dopaminergic receptors on obesity-related phenotypes. Taken together, the main findings of this review indicated that the genes encoding the DRD2 and DRD4 receptors may be the most relevant in the context of obesity and related phenotypes. However, obesity is a complex and multifactorial disease and new studies are still being conducted to better understand the impact of dopamine on obesity-related outcomes. It is also important to note that these effects can be specific to subgroups of patients and that other factors, in addition to genetic variants, must be considered. (AU)

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RESUMEN El síndrome neuroléptico maligno like o crisis acinética es una rara y potencialmente letal complicación del abandono de medicación de los pacientes con enfermedad de Parkinson. Se presenta el caso clínico de un paciente de sexo masculino de 52 años de edad, con antecedente de enfermedad de Parkinson de 10 años de evolución que se encuentra en tratamiento con levodopa-carbidopa. Acude a consultar por disminución del estado de conciencia y rigidez muscular generalizada, relacionado con el abandono de medicación 7 días antes del inicio de los síntomas.

ABSTRACT Neuroleptic malignant-like syndrome or akinetic crisis is a rare and potentially lethal complication of the withdrawal of medication of patients with Parkinson's disease. We present the clinical case of 52-year man with 10-year history of Parkinson's disease who is being treated with levodopa-carbidopa. He consults for decreased level of consciousness and general muscular rigidity, related to the withdrawal of the medication 7 days before the onset of symptoms.